As cliché as it may sound, I don't know how but I've managed to hang around with the wrong crowd more than once. That's the funny thing about crowds, you tend to go with the flow and before you know it, you're hanging out with a new group of "friends" but you don't know how you got there. It's a bit like it flashes before you eyes.
It's hard to know whether they are the wrong crowd for you, as it may not be that there is anything wrong with them. They could just not be the right crowd for you. Personally for me I know when a crowd isn't the "right" crowd for me as they either have no motivation to become a better person or they have a different way of living. There's nothing wrong with these qualities, it's just that I prefer to surround myself with positive people. I tend to be a fairly independent person, so I do tend to explore more often when it comes to crowds. I also find by mixing in a variety of different crowds you can really learn a lot about yourself and people from different backgrounds.
No matter how old you get you will always be faced with crowds, they tend to always be there no matter what, whether you're at work or with old friends, people will always tend to be in a crowd. So whether you're like me and you can easily get into the wrong crowd without realising or you prefer to make your own crowd, always try to reflect on where you are and whether you are in the right place for you. I am hoping to develop more of these reflecting skills in the near future. It's a great technique to try if you are not feeling like you are achieving the best you.